JP6718539B1 - Mold powder - Google Patents
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- JP6718539B1 JP6718539B1 JP2019079342A JP2019079342A JP6718539B1 JP 6718539 B1 JP6718539 B1 JP 6718539B1 JP 2019079342 A JP2019079342 A JP 2019079342A JP 2019079342 A JP2019079342 A JP 2019079342A JP 6718539 B1 JP6718539 B1 JP 6718539B1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
【課題】 高品質な鋳片の連続鋳造の安定操業に資するべく、スラグに求められる３要件が高度に調和されたモールドパウダーを提供すること。（要件１）凝固シェルとモールドの間の潤滑を保つこと（要件２）粘度と界面張力を適切に保ち、溶鋼に巻き込まれないこと（要件３）凝固シェルからモールドへの熱流束を制御し、適切な冷却速度を保つこと【解決手段】 モールドパウダーは、ＳｉＯ２とＣａＯを主成分として含み、ＣａＯのＳｉＯ２に対する質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下であり、Ｆ及びＡｌ２Ｏ３の含有量がそれぞれ５．０〜１４．０質量％、６．０〜１４．０質量％であり、ＦのＡｌ２Ｏ３に対する質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上であり、ＭｇＯの含有量が２．０〜１４．０質量％であり、Ｎａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜２．０質量％である。【選択図】 なしPROBLEM TO BE SOLVED: To provide a mold powder in which three requirements required for slag are highly harmonized in order to contribute to stable operation of continuous casting of high quality slab. (Requirement 1) Maintain lubrication between the solidified shell and the mold (Requirement 2) Maintain viscosity and interfacial tension appropriately and do not get caught in molten steel (Requirement 3) Control the heat flux from the solidified shell to the mold, Maintaining an appropriate cooling rate A mold powder contains SiO2 and CaO as main components, and the mass ratio of CaO to SiO2 (CaO/SiO2) is 0.9 or more and 1.6 or less, and F and Al2O3. Are 5.0 to 14.0 mass% and 6.0 to 14.0 mass %, respectively, the mass ratio of F to Al2O3 (F/Al2O3) is 0.8 or more, and the content of MgO is Is 2.0 to 14.0% by mass, and the total content of Na2O and Li2O is 0.0 to 2.0% by mass. [Selection diagram] None
Description
本発明は、鋼の連続鋳造に適するモールドパウダーに関する。 The present invention relates to a mold powder suitable for continuous casting of steel.
鋼の連続鋳造とは、溶鋼を連続鋳造機のモールドに流し込んで冷却、凝固させながら、凝固したシェル（凝固シェル）をモールドの下方向に引き抜くことを連続的に行うことにより、鋼を連続的に鋳造することをいう。モールド内の溶鋼の表面には、粉末状又は顆粒状のモールドパウダーが添加される。モールドパウダーは溶鋼の熱によって溶融し（以下、溶融している状態のモールドパウダーを「パウダースラグ」又は「スラグ」とよぶ。）、スラグは凝固シェルとモールドの間に流入し、フィルム（スラグフィルム）に変化する。モールドパウダーの主な役割は（１）溶鋼表面の保温及び酸化防止、（２）溶鋼から浮上する非金属介在物の吸収及び溶鋼の清浄化、（３）凝固シェルとモールドの間の潤滑の保持、（４）凝固シェルからモールドへの熱流束の制御等である。 Continuous casting of steel refers to continuous casting of steel by pouring molten steel into the mold of a continuous casting machine, cooling and solidifying it, and continuously pulling out the solidified shell (solidified shell) in the downward direction of the mold. It means casting in. Powdered or granular mold powder is added to the surface of the molten steel in the mold. The mold powder is melted by the heat of the molten steel (hereinafter, the melted mold powder is referred to as “powder slag” or “slag”), and the slag flows between the solidified shell and the mold to form a film (slag film). ). The main functions of the mold powder are (1) heat retention and oxidation prevention of the molten steel surface, (2) absorption of non-metallic inclusions floating from the molten steel and cleaning of the molten steel, (3) maintenance of lubrication between the solidified shell and the mold. (4) Control of heat flux from the solidified shell to the mold.
スラグが凝固シェルとモールドの間に流入する駆動力は、モールドのオシレーション（振動）、凝固シェルの引き抜きによる引き込み及びスラグの自重であるが、高品質な鋳片の連続鋳造の安定操業に資するには、特に、以下の３つの要件を高度に調和させる必要がある（以下、「３要件」とよぶ。）。
（要件１）凝固シェルとモールドの間の潤滑を保つこと
（要件２）粘度と界面張力を適切に保ち、溶鋼に巻き込まれないこと
（要件３）凝固シェルからモールドへの熱流束を制御し、適切な冷却速度を保つこと
The driving force that the slag flows between the solidified shell and the mold is the oscillation (vibration) of the mold, the withdrawal of the solidified shell and the slag's own weight, but it contributes to the stable operation of continuous casting of high quality slabs. In particular, it is necessary to highly harmonize the following three requirements (hereinafter referred to as “3 requirements”).
(Requirement 1) Maintain lubrication between the solidified shell and the mold (Requirement 2) Maintain viscosity and interfacial tension appropriately and do not get caught in molten steel (Requirement 3) Control the heat flux from the solidified shell to the mold, Maintaining proper cooling rate
要件１を満たすためにはスラグの粘度は低い方が好ましい。しかし、スラグの粘度が低いとスラグが溶鋼中に巻き込まれやすくなり、鋳片品質が低下する。つまり、要件２を満たさなくなる。そこで、スラグ巻き込みによる鋳片欠陥の低減が特に求められる極低炭素鋼、低炭素鋼では要件２を満たすためにスラグの高粘度化が指向される。特許文献１では、粘度だけでなく、表面張力を高めることが提案され、実施例には、１２５０℃の表面張力が２９０〜３１０ｄｙｎｅ／ｃｍのスラグが開示されている。特許文献２では、表面張力を高める手段として、ＭｇＯ含有量を増加させることが開示されている。 In order to satisfy the requirement 1, it is preferable that the viscosity of the slag is low. However, if the viscosity of the slag is low, the slag is likely to be caught in the molten steel, and the quality of the slab deteriorates. That is, the requirement 2 is not satisfied. Therefore, for extremely low carbon steels and low carbon steels, which are particularly required to reduce slab defects due to slag entrainment, higher slag viscosity is aimed to satisfy Requirement 2. Patent Document 1 proposes to increase not only the viscosity but also the surface tension, and Examples disclose a slag having a surface tension of 1250° C. of 290 to 310 dyne/cm. Patent Document 2 discloses increasing the MgO content as a means of increasing the surface tension.
要件３を満たすためにスラグフィルムへの結晶の析出が指向される。スラグフィルムに結晶が析出せず、ガラス質であると凝固シェルからモールドへの熱流束は大きく、結晶が析出し、結晶質であると熱流束は小さくなる。また、結晶の種類によっても凝固シェルからモールドへの熱流束は異なる。したがって、要件３を満たすには、熱流束を小さくする特定の結晶種を安定的に析出させる必要がある。鋳片からモールドへの熱流束が安定しないとモールド内温度の乱れが大きくなり、ブレークアウト予知システムの警報が発生するなど、操業が不安定になり生産性が低下する。特許文献３では、最適な結晶種としてカスピダイン（Cuspidine：３ＣａＯ・２ＳｉＯ２・ＣａＦ２）が提案されている。 To satisfy the requirement 3, the precipitation of crystals on the slag film is directed. If crystals are not deposited on the slag film and they are glassy, the heat flux from the solidified shell to the mold is large, and if crystals are deposited, if they are crystalline, the heat flux is small. The heat flux from the solidified shell to the mold also differs depending on the type of crystal. Therefore, in order to satisfy the requirement 3, it is necessary to stably deposit a specific crystal seed that reduces the heat flux. If the heat flux from the slab to the mold is not stable, the temperature inside the mold will be greatly disturbed, which will cause an alarm in the breakout prediction system, resulting in unstable operation and reduced productivity. Patent Document 3 proposes caspidine (Cuspidine: 3CaO.2SiO 2 .CaF 2 ) as an optimum crystal species.
しかし、特許文献１に開示されるスラグは、依然として溶鋼中への巻き込みが完全に解消されておらず、要件１、２の両立が不十分である。また、カスピダインが析出しにくいため、要件３も不十分である。さらに、特許文献２、３に開示されたスラグは、表面張力を十分高めることができないため、溶鋼中への巻き込みが解消されず、要件１、２の両立が不十分である。 However, in the slag disclosed in Patent Document 1, the entrainment in molten steel has not been completely eliminated, and compatibility of requirements 1 and 2 is insufficient. Further, the requirement 3 is also insufficient because caspodyne is hard to precipitate. Further, since the slags disclosed in Patent Documents 2 and 3 cannot sufficiently increase the surface tension, the entrainment in molten steel cannot be eliminated, and the requirements 1 and 2 are not satisfied at the same time.
本発明の態様は上記実状を鑑みてなされたものであり、本発明の目的は、高品質な鋳片の連続鋳造の安定操業に資するべく、スラグに求められる３要件が高度に調和されたモールドパウダーを提供することである。 Aspects of the present invention have been made in view of the above circumstances, and an object of the present invention is to provide a mold in which three requirements required for slag are highly harmonized in order to contribute to stable operation of continuous casting of high quality slabs. Is to provide powder.
なお、本明細書に示すモールドパウダーの化学組成は加熱される前のものであり、ＦとＣ以外の成分については酸化物換算での質量％で表し、Ｆについては単体換算での質量％で表し、Ｃについては炭素原料として添加されるものの質量％と、炭酸塩等として添加されるものの炭素単体換算での質量％とを合計した全炭素量（トータルカーボン）で表す。 The chemical composition of the mold powder shown in the present specification is that before heating, and the components other than F and C are represented by mass% in terms of oxide, and F is mass% in terms of simple substance. C is expressed as the total carbon amount (total carbon), which is the sum of the mass% of those added as a carbon raw material and the mass% of carbonaceous substances added as a simple substance of carbon.
本発明の一の態様は、ＳｉＯ２とＣａＯを主成分として含み、ＣａＯのＳｉＯ２に対する質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下であり、Ｆ及びＡｌ２Ｏ３の含有量がそれぞれ５．０〜１４．０質量％、６．０〜１４．０質量％であり、ＦのＡｌ２Ｏ３に対する質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上であり、ＭｇＯの含有量が２．０〜１４．０質量％であり、Ｎａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜２．０質量％であり、１３００℃における粘度及び表面張力がそれぞれ０．２０Ｐａ・ｓ以上及び３６０ｍＮ／ｍ以上であり、析出する主結晶種がカスピダイン（Cuspidine：３ＣａＯ・２ＳｉＯ２・ＣａＦ２）であることを特徴とするモールドパウダーに関する。 One aspect of the present invention comprises SiO 2 and CaO as main components, a mass ratio of SiO 2 CaO (CaO / SiO 2) is 0.9 to 1.6, the F and Al 2 O 3 5.0 to 14.0% by weight content of each is from 6.0 to 14.0 wt%, the weight ratio Al 2 O 3 of F (F / Al 2 O 3 ) is located at least 0.8 , The content of MgO is 2.0 to 14.0 mass %, the total content of Na 2 O and Li 2 O is 0.0 to 2.0 mass %, and the viscosity and surface tension at 1300° C. Are 0.20 Pa·s or more and 360 mN/m or more, respectively, and the main crystal species to be precipitated are caspidine (Cuspidine: 3CaO·2SiO 2 ·CaF 2 ).
モールドパウダーが上記要件を全て満たすことにより、スラグに求められる３要件を高度に調和させることができる。モールドパウダーは、スラグ巻き込みによる鋳片欠陥を減少させるとともに、モールド内温度の乱れによるブレークアウト予知警報の発生を抑制することができるため、高品質な鋳片の連続鋳造の安定操業に資する。 When the mold powder satisfies all the above requirements, the three requirements required for the slag can be highly harmonized. Mold powder contributes to stable operation of continuous casting of high quality slabs because it can reduce slab defects due to slag entrainment and suppress the occurrence of breakout prediction warnings due to temperature fluctuations in the mold.
以下、本発明の好適な実施形態について詳細に説明する。なお、以下に説明する本実施形態は、特許請求の範囲に記載された本発明の内容を不当に限定するものではなく、本実施形態で説明される構成のすべてが本発明の解決手段として必須であるとは限らない。 Hereinafter, preferred embodiments of the present invention will be described in detail. Note that the present embodiment described below does not unreasonably limit the content of the present invention described in the claims, and all the configurations described in the present embodiment are essential as a solution means of the present invention. Not necessarily.
本実施形態のモールドパウダーは、ＳｉＯ２とＣａＯを主成分として含み、ＣａＯのＳｉＯ２に対する質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下であり、Ｆ及びＡｌ２Ｏ３の含有量がそれぞれ５．０〜１４．０質量％、６．０〜１４．０質量％であり、ＦのＡｌ２Ｏ３に対する質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上であり、ＭｇＯの含有量が２．０〜１４．０質量％であり、Ｎａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜２．０質量％であり、１３００℃における粘度及び表面張力がそれぞれ０．２０Ｐａ・ｓ以上及び３６０ｍＮ／ｍ以上であり、析出する主結晶種がカスピダイン（Cuspidine：３ＣａＯ・２ＳｉＯ２・ＣａＦ２）である。 Mold powder of the present embodiment includes a SiO 2 and CaO as main components, a mass ratio of SiO 2 CaO (CaO / SiO 2) is 0.9 to 1.6, the F and Al 2 O 3 5.0 to 14.0% by weight content of each is from 6.0 to 14.0 wt%, the weight ratio Al 2 O 3 of F (F / Al 2 O 3 ) is located at least 0.8 , The content of MgO is 2.0 to 14.0 mass %, the total content of Na 2 O and Li 2 O is 0.0 to 2.0 mass %, and the viscosity and surface tension at 1300° C. Are 0.20 Pa·s or more and 360 mN/m or more, respectively, and the main crystal species to be precipitated is caspidine (Cuspidine: 3CaO·2SiO 2 ·CaF 2 ).
［質量比（ＣａＯ／ＳｉＯ２）］
モールドパウダーはＳｉＯ２とＣａＯを主成分として含有する。ＣａＯのＳｉＯ２に対する質量比（ＣａＯ／ＳｉＯ２）は０．９以上１．６以下であり、好ましくは１．０以上１．５以下であり、より好ましくは１．０以上１．４以下である。質量比（ＣａＯ／ＳｉＯ２）が０．９未満の場合、スラグの表面張力を高く保つことができないため、要件１、２が両立せず、鋳片の品質が悪化しやすい。一方、質量比（ＣａＯ／ＳｉＯ２）が１．６を超える場合、スラグの粘度が大きく低下するため、要件１、２が両立せず、鋳片の品質が悪化しやすい。さらに、凝固温度が大きく上昇し、凝固しやすくなるため、ブレークアウトの発生リスクが高まる。
[Mass ratio (CaO/SiO 2 )]
The mold powder contains SiO 2 and CaO as main components. Weight ratio of SiO 2 CaO (CaO / SiO 2) is 0.9 to 1.6, preferably from 1.0 to 1.5, more preferably 1.0 to 1.4 is there. When the mass ratio (CaO/SiO 2 ) is less than 0.9, the surface tension of the slag cannot be kept high, and thus requirements 1 and 2 are not compatible and the quality of the cast piece is likely to deteriorate. On the other hand, when the mass ratio (CaO/SiO 2 ) exceeds 1.6, the viscosity of the slag is significantly reduced, and requirements 1 and 2 are not compatible with each other, and the quality of the cast piece is likely to deteriorate. In addition, the solidification temperature rises significantly and the solidification becomes easier, which increases the risk of breakout.
［Ｆ］
Ｆの含有量は５．０〜１４．０質量％であり、好ましくは６．０〜１３．０質量％であり、より好ましくは７．０〜１２．０質量％である。Ｆの含有量が５．０質量％未満の場合、結晶としてカスピダインが析出しにくくなり、ゲーレナイト（Gehlenite；Ｃａ２Ａｌ２ＳｉＯ７）、アケルマナイト（Akermanite；Ｃａ２ＭｇＳｉ２Ｏ７）、ダイカルシウムシリケート（Dicalcium silicate；２ＣａＯ・ＳｉＯ２）等が析出し、要件３を満たさなくなる。一方、Ｆの含有量が１４．０質量％を超える場合、スラグの粘度と表面張力が大きく低下するため、要件１、２が両立しなくなる他、浸漬ノズルの溶損が増大する。
[F]
The content of F is 5.0 to 14.0 mass%, preferably 6.0 to 13.0 mass%, and more preferably 7.0 to 12.0 mass%. When the F content is less than 5.0% by mass, it becomes difficult for cuspidine to precipitate as crystals, and gehlenite (Gehlenite; Ca 2 Al 2 SiO 7 ), akermanite (Akermanite; Ca 2 MgSi 2 O 7 ), dicalcium silicate. (Dicalcium silicate; 2CaO·SiO 2 ) etc. will be deposited and requirement 3 will not be satisfied. On the other hand, when the content of F exceeds 14.0 mass %, the viscosity and the surface tension of the slag are greatly reduced, and thus requirements 1 and 2 are not compatible with each other and melting loss of the immersion nozzle is increased.
［Ａｌ２Ｏ３］
Ａｌ２Ｏ３の含有量は６．０〜１４．０質量％であり、好ましくは６．０〜１３．０質量％であり、より好ましくは７．０〜１２．０質量％である。Ａｌ２Ｏ３の含有量が６．０質量％未満の場合、粘度、表面張力を高くすることができないため、要件１、２が両立しなくなる。Ａｌ２Ｏ３含有量が１４．０質量％を超える場合、カスピダインよりもゲーレナイトが析出しやすくなり、要件３を満たさなくなる。
[Al 2 O 3 ]
The content of Al 2 O 3 is 6.0 to 14.0 mass%, preferably 6.0 to 13.0 mass%, and more preferably 7.0 to 12.0 mass%. When the content of Al 2 O 3 is less than 6.0% by mass, the viscosity and the surface tension cannot be increased, and thus requirements 1 and 2 are not compatible. When the Al 2 O 3 content exceeds 14.0 mass %, gehlenite is more likely to precipitate than in caspodyne, and the requirement 3 is not satisfied.
［質量比（Ｆ／Ａｌ２Ｏ３）］
質量比（Ｆ／Ａｌ２Ｏ３）は、０．８以上であり、より好ましくは０．９以上であり、より好ましくは１．０以上である。質量比（Ｆ／Ａｌ２Ｏ３）が０．８未満の場合、ゲーレナイトが著しく析出しやすくなり、要件３を満たさなくなる。質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上の場合、カスピダインが析出しやすいため、要件３を満たし、連続鋳造の操業を安定化させることができる。
[Mass ratio (F/Al 2 O 3 )]
The mass ratio (F/Al 2 O 3 ) is 0.8 or more, more preferably 0.9 or more, and more preferably 1.0 or more. When the mass ratio (F/Al 2 O 3 ) is less than 0.8, gehlenite is apt to precipitate significantly, and the requirement 3 cannot be satisfied. When the mass ratio (F/Al 2 O 3 ) is 0.8 or more, caspodyne is likely to precipitate, so that requirement 3 can be satisfied and the continuous casting operation can be stabilized.
［ＭｇＯ］
ＭｇＯの含有量は２．０〜１４．０質量％であり、好ましくは３．０〜１３．０質量％、より好ましくは４．０〜１２．０質量％、特に好ましくは４．０〜７．０質量％である。ＭｇＯは融点を下げる点でアルカリ金属酸化物と共通し、表面張力を高める点でアルカリ金属酸化物と異なる。本実施形態の組成はモールドパウダーの融点を下げるアルカリ金属酸化物の含有量が少ないため、高い表面張力を保つ融点調整剤として好適である。ＭｇＯの含有量が２．０質量％未満の場合、融点が高くなり、要件１、２を満たさなくなる。ＭｇＯの含有量が１４．０質量％を超える場合、カスピダインの析出が低下し、アケルマナイト等のＭｇＯを含む結晶が析出しやすくなるため、要件３を満たさなくなる。
[MgO]
The content of MgO is 2.0 to 14.0 mass%, preferably 3.0 to 13.0 mass%, more preferably 4.0 to 12.0 mass%, and particularly preferably 4.0 to 7 mass%. It is 0.0% by mass. MgO is common with alkali metal oxides in that it lowers the melting point, and is different from alkali metal oxides in that it enhances surface tension. The composition of the present embodiment contains a small amount of the alkali metal oxide that lowers the melting point of the mold powder, and is therefore suitable as a melting point adjusting agent that maintains a high surface tension. When the content of MgO is less than 2.0% by mass, the melting point becomes high and the requirements 1 and 2 cannot be satisfied. When the content of MgO exceeds 14.0 mass %, the precipitation of caspodyne is lowered and the crystals containing MgO such as akermanite are likely to be precipitated, so that the requirement 3 is not satisfied.
［Ｎａ２Ｏ＋Ｌｉ２Ｏ］
Ｎａ２ＯとＬｉ２Ｏの含有量の合計は０．０〜２．０質量％であり、好ましくは０．０〜１．５質量％以下であり、より好ましくは０．０〜１．０質量％である。Ｎａ２ＯとＬｉ２Ｏの含有量の合計が２．０質量％を超える場合、表面張力が低下し、要件２を満たさなくなる。
[Na 2 O+Li 2 O]
The total content of Na 2 O and Li 2 O is 0.0 to 2.0 mass%, preferably 0.0 to 1.5 mass% or less, and more preferably 0.0 to 1.0. It is% by mass. When the total content of Na 2 O and Li 2 O exceeds 2.0% by mass, the surface tension decreases and the requirement 2 cannot be satisfied.
［粘度］
１３００℃におけるスラグの粘度は０．２０Ｐａ・ｓ以上であり、好ましくは０．３０Ｐａ・ｓ以上である。１３００℃におけるスラグの粘度が０．２０Ｐａ・ｓ未満の場合、要件２を満たさず、スラグの巻き込みが増大する。スラグ巻き込みを抑制するにはモールドパウダーの粘度は高い方が望ましいため、本実施形態の組成範囲であれば、上限は特に規定するものではないが、０．７５Ｐａ・ｓが上限である。
[viscosity]
The viscosity of slag at 1300° C. is 0.20 Pa·s or more, preferably 0.30 Pa·s or more. When the viscosity of the slag at 1300° C. is less than 0.20 Pa·s, the requirement 2 is not satisfied and the slag entrainment increases. Since it is desirable that the viscosity of the mold powder be high in order to suppress slag entrapment, the upper limit is not particularly specified within the composition range of the present embodiment, but 0.75 Pa·s is the upper limit.
［表面張力］
１３００℃におけるスラグの表面張力は３６０ｍＮ／ｍ以上である。１３００℃におけるスラグの表面張力が３６０ｍＮ／ｍ未満の場合、要件２を満たさず、スラグの巻き込みによって鋳片品質が低下する。
[surface tension]
The surface tension of the slag at 1300° C. is 360 mN/m or more. When the surface tension of the slag at 1300° C. is less than 360 mN/m, the requirement 2 is not satisfied, and the quality of the cast product is deteriorated due to the inclusion of the slag.
［主結晶種］
スラグフィルムに析出する主結晶種はカスピダインである。カスピダイン以外の結晶が主結晶種であると熱流束の制御が困難となり、要件３を満たさなくなる。したがって、ブレークアウト予知警報の発生が多くなり、連続鋳造の操業が不安定になる。
[Main crystal type]
The main crystal seed deposited on the slag film is caspidine. When crystals other than caspodyne are the main crystal seeds, it becomes difficult to control the heat flux, and requirement 3 cannot be satisfied. Therefore, the breakout prediction warning is frequently generated, and the continuous casting operation becomes unstable.
［モールドパウダーの原料］
本実施形態のモールドパウダーの原料はＣａＯ−ＳｉＯ２基材原料、シリカ原料、フラックス原料、炭素原料、及び／又はその他の原料で構成される。ＣａＯ−ＳｉＯ２基材原料としては、例えば、合成珪酸カルシウム、ウォラストナイト、リンスラグ、高炉スラグ、ダイカルシウムシリケート、炭酸カルシウム、石灰石、生石灰、ポルトランドセメント等のセメント類等が挙げられる。シリカ原料としては、例えば、パーライト、フライアッシュ、珪砂、長石、珪石、珪藻土、ガラス粉、シリカフューム、シリカフラワー等が挙げられる。フラックス原料は、軟化点、粘度及び／又は結晶化温度を調整する役割を有し、例えば、フッ化ナトリウム、フッ化リチウム、氷晶石、蛍石（フッ化カルシウム）、フッ化マグネシウム等の弗化物、炭酸ナトリウム、炭酸リチウム、炭酸マグネシウム等の炭酸塩、ホウ酸、ホウ砂、コレマナイト等が挙げられる。炭素原料は、溶融速度を調整する役割を有し、例えば、コークス、グラファイト、カーボンブラック等が挙げられる。その他の原料としては、マグネシア、アルミナ等が挙げられる。モールドパウダーの原料には不可避成分として微量のＦｅ２Ｏ３、ＴｉＯ２、ＭｎＯ、Ｋ２Ｏ、Ｃｒ２Ｏ３、Ｐ２Ｏ５、Ｓ等が含まれてもよい。モールドパウダーの形態は特に限定されず、例えば、粉末、押し出し成形顆粒、中空スプレー顆粒、撹拌造粒等が挙げられる。
[Mold powder ingredients]
The raw material of the mold powder of this embodiment is composed of a CaO—SiO 2 base material, silica raw material, flux raw material, carbon raw material, and/or other raw material. The CaO-SiO 2 substrate material, e.g., synthetic calcium silicate, wollastonite, slag, blast furnace slag, dicalcium silicate, calcium carbonate, limestone, lime, include cements such as Portland cement. Examples of the silica raw material include perlite, fly ash, silica sand, feldspar, silica stone, diatomaceous earth, glass powder, silica fume, silica flour and the like. The flux raw material has a role of adjusting the softening point, the viscosity and/or the crystallization temperature. For example, sodium fluoride, lithium fluoride, cryolite, fluorite (calcium fluoride), magnesium fluoride, and other fluorine materials. Compounds, carbonates such as sodium carbonate, lithium carbonate and magnesium carbonate, boric acid, borax, colemanite and the like. The carbon raw material has a role of adjusting the melting rate, and examples thereof include coke, graphite, and carbon black. Examples of other raw materials include magnesia and alumina. The raw material of the mold powder may contain trace amounts of Fe 2 O 3 , TiO 2 , MnO, K 2 O, Cr 2 O 3 , P 2 O 5 , S and the like as unavoidable components. The form of the mold powder is not particularly limited, and examples thereof include powder, extrusion-molded granules, hollow spray granules, and stirring granulation.
以下、本発明の実施例について詳細に説明する。 Hereinafter, examples of the present invention will be described in detail.
［実験方法］
モールドパウダーを用いて鋼の連続鋳造を行った。表１に、用いたモールドパウダーの組成を示す。実施例１〜１６は本発明の実施例であり、比較例１〜１１は本発明の比較例である。
Continuous casting of steel was performed using mold powder. Table 1 shows the composition of the mold powder used. Examples 1 to 16 are examples of the present invention, and Comparative Examples 1 to 11 are comparative examples of the present invention.
実施例１〜１６は、ＳｉＯ２とＣａＯを主成分として含み、ＣａＯのＳｉＯ２に対する質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下であり、Ｆ及びＡｌ２Ｏ３の含有量がそれぞれ５．０〜１４．０質量％、６．０〜１４．０質量％であり、ＦのＡｌ２Ｏ３に対する質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上であり、ＭｇＯの含有量が２．０〜１４．０質量％であり、Ｎａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜２．０質量％である。 Examples 1-16 includes SiO 2 and CaO as main components, a mass ratio of SiO 2 CaO (CaO / SiO 2) is 0.9 to 1.6, containing the F and Al 2 O 3 the amount respectively 5.0 to 14.0 wt%, a 6.0 to 14.0 wt%, the weight ratio Al 2 O 3 of F (F / Al 2 O 3 ) is not less than 0.8, The content of MgO is 2.0 to 14.0 mass %, and the total content of Na 2 O and Li 2 O is 0.0 to 2.0 mass %.
一方、比較例１〜２は質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上を満たさない。また、比較例２、１１はＦの含有量がそれぞれ５．０〜１４．０質量％を満たさない。また、比較例３、９〜１０はＡｌ２Ｏ３の含有量が６．０〜１４．０質量を満たさない。また、比較例４、１０はＭｇＯの含有量が２．０〜１４．０質量％を満たさない。また、比較例５〜６はＮａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜２．０質量％を満たさない。また、比較例７〜８は質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下を満たさない。 On the other hand, in Comparative Examples 1 and 2, the mass ratio (F/Al 2 O 3 ) does not satisfy 0.8 or more. In addition, Comparative Examples 2 and 11 do not satisfy the F contents of 5.0 to 14.0 mass %, respectively. In addition, Comparative Examples 3 and 9 to 10 do not satisfy the Al 2 O 3 content of 6.0 to 14.0 mass. Further, in Comparative Examples 4 and 10, the content of MgO does not satisfy 2.0 to 14.0 mass %. Further, in Comparative Examples 5 to 6, the total content of Na 2 O and Li 2 O does not satisfy 0.0 to 2.0 mass %. Further, in Comparative Examples 7 to 8, the mass ratio (CaO/SiO 2 ) does not satisfy 0.9 or more and 1.6 or less.
表２に、連続鋳造の鋳造条件、即ち、モールドサイズ、鋼種、鋳造速度を示す。表２の鋼種の「極低炭素」、「低炭素」、「高炭素」はカーボン濃度がそれぞれ０．０１質量％以下、０．０１〜０．０８質量％、０．２０質量％以上の炭素綱である。
実施例と比較例の鋳造条件はほぼ同様とした。 The casting conditions of the example and the comparative example were almost the same.
［評価方法］
モールドパウダー（スラグ）及び連続鋳造によって得られた鋳片について、以下の項目の評価を行った。
[Evaluation method]
The following items were evaluated for the mold powder (slag) and the slab obtained by continuous casting.
＜粘度＞
モールドパウダー（スラグ）の粘度を、球引き上げ法により測定した。即ち、１３００℃のスラグ中に直径１０ｍｍの白金球を吊り下げ、０．８５ｃｍ／ｓの速さで白金球を引き上げたときの荷重から粘度を求めた。
<Viscosity>
The viscosity of the mold powder (slag) was measured by the ball lifting method. That is, the viscosity was obtained from the load when a platinum ball having a diameter of 10 mm was suspended in slag at 1300° C. and the platinum ball was pulled up at a speed of 0.85 cm/s.
＜表面張力＞
モールドパウダー（スラグ）の表面張力を、リング法により測定した。即ち、１３００℃のスラグ中に直径１０ｍｍの白金リングを浸漬し、０．８５ｃｍ／ｓの速さで白金リングを引き上げ、白金リングがスラグ液面から離れて液滴が切断する瞬間に示す最大荷重から表面張力を求めた。
<Surface tension>
The surface tension of the mold powder (slag) was measured by the ring method. That is, a platinum ring with a diameter of 10 mm is immersed in slag at 1300° C., the platinum ring is pulled up at a speed of 0.85 cm/s, and the maximum load shown at the moment when the platinum ring separates from the liquid surface of the slag and droplets are cut off. The surface tension was obtained from
＜主結晶種＞
主結晶種は、１３００℃で溶融状態のスラグ１００ｇを鉄製容器に流し込んで急冷し、得られた凝固スラグのＸ線回折パターンにより同定した。
<Main crystal type>
The main crystal seed was identified by an X-ray diffraction pattern of the solidified slag obtained by pouring 100 g of molten slag at 1300° C. into an iron container and quenching.
＜鋳片品質＞
鋳片の品質は、スラグ巻き込みによる鋳片欠陥の発生率が０．５％以下を「優：★★★」、０．５％を超え１％未満を「良：★★」、１％を超え３％未満を「可：★」、３％以上を「不可：×」とした。
<Slab quality>
The quality of the slab is "excellent:★★★" when the occurrence rate of slab defects due to slag entrainment is 0.5% or less, "good:★★" when it exceeds 0.5% and less than 1%, and 1%. Exceeding less than 3% was evaluated as “OK:★” and 3% or more was evaluated as “No:X”.
＜操業安定性＞
連続鋳造の操業安定性は、１００チャージ（１チャージ３００ｔ）を鋳造してブレークアウト予知警報の発生数が０回で、モールド内温度の乱れもなければ「優：★★★」、ブレークアウト予知警報の発生数が０回だがモールド内温度の乱れが多少あれば「良：★★」、ブレークアウト予知警報の発生数が１回であれば「可：★」、ブレークアウト予知警報の発生数が２回以上であれば「不可：×」とした。
<Operational stability>
As for the operational stability of continuous casting, 100 charges (1 charge 300t) were cast, the number of breakout prediction alarms was 0, and if there was no disturbance in the mold temperature, "Excellent: ★★★", breakout prediction If the number of alarms is 0, but the temperature in the mold is slightly disturbed, it is "Good: ★★", and if the number of breakout prediction alarms is 1, it is "OK: ★", the number of breakout prediction alarms is generated. If was twice or more, it was determined to be "impossible: x".
＜総合評価＞
総合評価は、鋳片品質、操業安定性の両者が「優：★★★」であれば「優：◎」、いずれかに「良：★★」もしくは「可：★」があり、「不可：×」がなければ「可：○」、いずれかに「不可：×」があれば「不可：×」とした。
<Comprehensive evaluation>
In the overall evaluation, if both the slab quality and the operational stability are "excellent:★★★", then "excellent: ◎", either is "good:★★" or "acceptable:★", and "impossible" If there is no: ×, it is judged as “OK: ○”, and if there is any “Improper: ×”, it is judged as “Improper: ×”.
［評価結果］
評価結果を表３に示す。
The evaluation results are shown in Table 3.
実施例１〜１６はいずれも１３００℃における粘度及び表面張力がそれぞれ０．２０Ｐａ・ｓ以上及び３６０ｍＮ／ｍ以上であり、析出する主結晶種がカスピダインであった。また、鋳片品質及び操業安定性は「優：★★★」〜「可：★」であり、総合評価は「優：◎」又は「可：○」であった。これは、３要件が高度に調和されたためと考えられる。 In each of Examples 1 to 16, the viscosity and the surface tension at 1300° C. were 0.20 Pa·s or more and 360 mN/m or more, respectively, and the main crystal seed to be precipitated was caspodyne. In addition, the slab quality and operation stability were "excellent:★★★" to "possible:★", and the overall evaluation was "excellent: ◎" or "possible:○". This is probably because the three requirements were highly harmonized.
一方、比較例１〜１１は操業安定性か鋳片品質のいずれかが「不可：×」であり、総合評価は「不可：×」であった。比較例１〜４は操業時にブレークアウト予知警報が多発し、操業安定性が「不可：×」であった。これは、主結晶種がカスピダインではないため、凝固シェルからモールドへの熱流束が適切でなく、要件３を満たさなかったと考えられる。比較例１〜３は質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下を下回り、主結晶種がゲーレナイトであった。また、比較例４はＡｌ２Ｏ３の含有量が６．０〜１４．０質量を上回り、主結晶種がアケルマナイトであった。 On the other hand, in Comparative Examples 1 to 11, either the operation stability or the slab quality was "impossible:x", and the comprehensive evaluation was "impossible:x". In Comparative Examples 1 to 4, breakout prediction warnings frequently occurred during operation, and the operation stability was “impossible: x”. It is considered that this is because the heat flux from the solidified shell to the mold was not appropriate and the requirement 3 was not satisfied because the main crystal seed was not caspodyne. In Comparative Examples 1 to 3, the mass ratio (CaO/SiO 2 ) was less than 0.9 and less than 1.6, and the main crystal seed was gehlenite. Further, in Comparative Example 4, the content of Al 2 O 3 exceeded 6.0 to 14.0 mass, and the main crystal seed was akermanite.
比較例５〜１１は鋳片品質が「不可：×」であった。これは、１３００℃における表面張力が３６０ｍＮ／ｍ以上を満たさないため、スラグの界面張力を適切に保つことができず、要件２を満たさなかったと考えられる。比較例５、６はＮａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜２．０質量％を上回り、表面張力が３６０ｍＮ／ｍ以上を満たさなかった。比較例７は（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下を上回り、粘度及び表面張力がそれぞれ０．２０Ｐａ・ｓ以上及び３６０ｍＮ／ｍ以上を満たさなかった。比較例８は（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下を下回り、表面張力が３６０ｍＮ／ｍ以上を満たさなかった。比較例９、１０はＡｌ２Ｏ３の含有量が６．０〜１４．０質量を下回り、表面張力が３６０ｍＮ／ｍ以上を満たさなかった。比較例１１はＦの含有量が５．０〜１４．０質量％を上回り、表面張力が３６０ｍＮ／ｍ以上を満たさなかった。 In Comparative Examples 5 to 11, the slab quality was "impossible: x". It is considered that this is because the surface tension at 1300° C. did not satisfy 360 mN/m or more, so that the interfacial tension of the slag could not be appropriately maintained and the requirement 2 was not satisfied. In Comparative Examples 5 and 6, the total content of Na 2 O and Li 2 O exceeded 0.0 to 2.0 mass %, and the surface tension did not satisfy 360 mN/m or more. In Comparative Example 7, (CaO/SiO 2 ) exceeded 0.9 or more and 1.6 or less, and the viscosity and the surface tension did not satisfy 0.20 Pa·s or more and 360 mN/m or more, respectively. In Comparative Example 8, (CaO/SiO 2 ) was less than 0.9 and less than 1.6, and the surface tension did not satisfy 360 mN/m or more. In Comparative Examples 9 and 10, the content of Al 2 O 3 was less than 6.0 to 14.0 mass, and the surface tension did not satisfy 360 mN/m or more. In Comparative Example 11, the F content exceeded 5.0 to 14.0 mass %, and the surface tension did not satisfy 360 mN/m or more.
なお、上記のように本実施形態について詳細に説明したが、本発明の新規事項及び効果から実体的に逸脱しない多くの変形が可能であることは当業者には容易に理解できるであろう。したがって、このような変形例はすべて本発明の範囲に含まれる。例えば、明細書において、少なくとも一度、より広義又は同義な異なる用語とともに記載された用語は、明細書のいかなる箇所においても、その異なる用語に置き換えられることができる。また、本実施形態の製造装置等の構成及び動作も本実施形態で説明したものに限定されず、種々の変形が可能である。 Although the present embodiment has been described above in detail, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Therefore, all such modifications are included in the scope of the present invention. For example, in the specification, a term described at least once together with a different term having a broader meaning or the same meaning can be replaced with the different term anywhere in the specification. Further, the configuration and operation of the manufacturing apparatus and the like of this embodiment are not limited to those described in this embodiment, and various modifications are possible.
Claims (3)
ＣａＯのＳｉＯ２に対する質量比（ＣａＯ／ＳｉＯ２）が０．９以上１．６以下であり、
Ｆ及びＡｌ２Ｏ３の含有量がそれぞれ５．０〜１４．０質量％、６．０〜１４．０質量％であり、
ＦのＡｌ２Ｏ３に対する質量比（Ｆ／Ａｌ２Ｏ３）が０．８以上であり、
ＭｇＯの含有量が４．０〜１２．０質量％であり、
Ｎａ２ＯとＬｉ２Ｏの含有量の合計が０．０〜１．３質量％であり、
１３００℃における粘度及び表面張力がそれぞれ０．２０Ｐａ・ｓ以上０．７５Ｐａ・ｓ以下及び３６０ｍＮ／ｍ以上であり、
１３００℃で溶融状態のスラグ１００ｇを鉄製容器に流し込んで急冷したときに析出する主結晶種がカスピダイン（Cuspidine：３ＣａＯ・２ＳｉＯ ２ ・ＣａＦ ２ ）であることを特徴とするモールドパウダー。 Contains SiO 2 and CaO as main components,
Weight ratio of SiO 2 CaO (CaO / SiO 2) is 0.9 to 1.6,
The contents of F and Al 2 O 3 are 5.0 to 14.0% by mass and 6.0 to 14.0% by mass, respectively.
Weight ratio Al 2 O 3 of F (F / Al 2 O 3 ) is not less than 0.8,
The content of MgO is 4.0 to 12.0 mass %,
Total 0.0 to 1.3% by mass of the content of Na 2 O and Li 2 O is,
The viscosity and the surface tension at 1300° C. are 0.20 Pa·s or more and 0.75 Pa·s or less and 360 mN/m or more, respectively,
1300 main crystal species to be precipitated when the slag 100g molten and quenched by pouring into an iron container ℃ is Kasupidain (Cuspidine: 3CaO · 2SiO 2 · CaF 2) mold powder according to claim der Rukoto.
前記Ｎａ ２ ＯとＬｉ ２ Ｏの含有量の合計が０．０〜１．０質量％であることを特徴とするモールドパウダー。 The mold powder according to claim 1, wherein
Mold powder characterized in that the total content of Na 2 O and Li 2 O is 0.0 to 1.0 mass % .
前記Ｆの含有量が８．２〜１４．０質量％であることを特徴とするモールドパウダー。 The mold powder according to claim 1 or 2, wherein
The mold powder, wherein the content of F is 8.2 to 14.0 mass % .
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